The invention relates generally to materials for reducing erosion, sediment replacement and/or construction, habitat replacement and/or construction, and more particularly to a barrier cap material, which may be used for these and/or other applications.
A significant number of lakes, ponds, reservoirs, lagoons, marshes, river beds and ocean areas near coastlines are contaminated with environmentally hazardous materials. Examples of such materials include polychlorinated biphenyls, white phosphorus, synthetic organic compounds, and various metals. Many of these materials, once introduced by one means or another, settle on the bottoms of such bodies of water and become attached to sediments. The resulting contaminated sediments are detrimental to the ecosystem, especially wildlife which utilizes the body of water, such as fish, foraging waterfowl and small vertebrates and invertebrates. In some cases the contaminants are slowly released from the sediments and re-introduced into the water column. Such sediment-borne contaminants can also adversely impact wetland or deepwater ecosystems indirectly through food-chain effects.
Remedial dredging and removal of contaminated sediments is an often used approach for addressing this problem. Dredging often alters the bottom contour, sediment stability, and habitat suitability. A number of other environmental impacts may be associated with remedial dredging including re-suspension of contaminated sediments into the overlying water column and incomplete removal of sediment contaminants from the uppermost, and most biologically active layers. Consequently, remedial dredging alone may be an insufficient and incomplete solution to the problem; however, post dredging capping may address remaining concerns. Additionally, some lake and ocean coastal areas, streams and rivers, and wetland areas are inherently more susceptible to increased erosion. The erosion results in an increased suspension of sediments into the system, a geotechnically unstable condition, and a net loss of terrestrial land area. To address these problems, materials such as sand, stone, other types of replacement sediments, or erosion prevention systems may be implemented. Often these materials are not geotechnically stable and result in increased erosion, are not appropriate to sustain adequate aquatic life, or are too expensive and/or labor intensive to implement. Consequently, the use of these materials to replace dredged materials and remedy erosion may not be sufficient.
A commercial product named AQUABLOK®, sold by AquaBlok, Ltd., Toledo, Ohio, can often be used as a replacement for, or in addition to, dredging replacement material or erosion control material. The product comprises a plurality of manufactured composite particles including a hydratable sealant material. The particles are applied on a surface, such as a recently dredged underwater surface. When the particles are hydrated they replace lost volume and habitat with a geotechnically stable erosion resistant layer. Various embodiments of the AQUABLOK® product and different applications for the product are described in U.S. Pat. Nos. 5,897,946, 6,386,796 and 6,558,081, which are incorporated by reference herein.
It would be desirable to provide additional barrier cap materials that are related to the AQUABLOK® product, yet which may have more versatility and be provided at a lower cost.